3rd generation partnership project (3GPP) long term evolution (LTE) is an improved version of a universal mobile telecommunication system (UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE.
A micro cell, a femto cell, and a pico cell, etc., having a small service area can be installed in a specific location of a macro cell having a wide coverage.
Due to mobility of a user equipment (UE) represented as a mobile device, quality of a currently provided service may deteriorate or a cell capable of providing a better service may be detected. Accordingly, the UE may move to a new cell, which is called performing of the mobility of the UE.
In order to perform the mobility, the UE persistently performs measurement on a serving cell and a neighboring cell. When the measurement result satisfies a condition for performing the mobility, the UE can receive an instruction from the serving cell and can directly perform the mobility.
Meanwhile, in order to perform measurement on a cell corresponding to a specific type, the UE performs the measurement in a state where a service received from the serving cell is suspended. In particular, in case of performing measurement on an inter-frequency cell, the measurement is performed on a frequency different from a frequency at which a service is previously received from the serving cell.
As such, since the measurement procedure performed by the UE is persistently performed by the UE even if the cell of the specific type does not exist nearby in practice, quality of a service provided to the UE may deteriorate. This is because an opportunity for receiving the service from the serving cell to perform the measurement is decreased. Accordingly, there is a need for a method for ensuring the quality of the service provided to the UE and for allowing the UE to properly perform the mobility.